Vehicle control apparatus

ABSTRACT

An apparatus for controlling an automotive vehicle including a target-drive-force setting portion operable to determine a target vehicle drive force, such that the determined target vehicle drive force permits a smooth change of an actual vehicle drive force with a change of the operating amount of the vehicle accelerating member, irrespective of a shifting action of the transmission, a first controlling portion having a relatively high operating response and operable to effect a transient control of a torque of the drive power source, and a second controlling portion having lower operating response than the first controlling portion but is capable of continuously controlling the torque of the drive power source, the second controlling portion being operable to effect a continuous control of the torque of the drive power source following the transient control by the first controlling portion, so that the actual vehicle drive force coincides with said target vehicle drive force after the shifting action of the transmission.

This application is based on Japanese Patent Application No. 2003-174039filed on Jun. 18, 2003, the contents of which are incorporated hereintoby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to a vehicle control apparatusincluding a drive-power-source-torque control portion for controlling atorque of a drive power source (e.g., engine) for a vehicle, and moreparticularly to techniques for determining a target vehicle drive torqueon the basis of an operating amount of a manually operated vehicleaccelerating member and a selected operating position of a transmissionhaving respective different speed ratios, so as to permit a smoothchange of the vehicle drive force with a change of the operating amountof the vehicle accelerating member, for thereby improving thedrivability of the vehicle, irrespective of a shifting action of thetransmission, that is, irrespective of a non-smooth change of the speedratio of the transmission.

2. Discussion of Related Art

In a vehicle including an automatic transmission having a plurality ofoperating positions having respective different speed ratios, wherein aselected one of the operating positions is automatically selected, thetransmission may suffer from a shock during a shifting action thereof.To reduce the shifting shock of the automatic transmission, a knownvehicle is provided with an engine output control apparatus arranged totemporarily control the torque of a drive power source in the form of anengine, so as to smooth a variation in the output torque of thetransmission. For example, JP-A-9-119328 discloses a technique wherein arelationship between an operating amount of a manually operated vehicleaccelerating member such as an accelerator pedal and an opening angle ofan electronically controlled throttle valve is temporarily changed toreduce the engine torque in the process of a shifting action of thetransmission, for reducing a change of the output torque of thetransmission in the process of the shifting action, to thereby minimizea shifting shock of the transmission.

JP-A-9-310627 discloses an engine output control apparatus for avehicle, wherein an electronically controlled throttle valve iscontrolled by an engine control unit according to an output signal of anaccelerator sensor, such that the output torque of an engine is reducedupon a shifting action of an automatic transmission, for reducing ashifting shock of the transmission.

Unlike a continuously variable transmission, an automatic transmissionhaving a plurality of operating positions having respective differentspeed ratios suffers from a considerably large amount of change of itsoutput torque before and after a shifting action thereof, due to anon-smooth abrupt change of the speed ratio from a value before theshifting action to a value after completion of the shifting action. Theconventional engine output control apparatus is not satisfactory in itscapability to minimize a drawback that the drivability of the vehicletends to be deteriorated due to a considerably large amount of change ofthe vehicle drive force upon a shifting action of the automatictransmission.

SUMMARY OF THE INVENTION

The present invention was made in the light of the background artdiscussed above. It is therefore an object of the present invention toprovide an apparatus for controlling a vehicle including an engine and atransmission having a plurality of operating positions having respectivespeed ratios, which apparatus is arranged to determine a target drivetorque of the vehicle on the basis of an operating amount of a manuallyoperated vehicle accelerating member and a selected one of the operatingpositions of the transmission, so as to permit a smooth change of thevehicle drive force with a change of the operating amount of the vehicleaccelerating member, for thereby improving the drivability of thevehicle, irrespective of a shifting action of the transmission.

The above object may be achieved according to the principle of thepresent invention, which provides an apparatus for controlling anautomotive vehicle having a drive power source, a transmission having aplurality of operating positions that are selectively established, and amanually operable vehicle accelerating member, comprising:

-   -   a target-drive-force setting portion operable to determine a        target vehicle drive force on the basis of an operating amount        of the manually operable vehicle accelerating member and a        presently selected one of the plurality of operating positions        of the transmission, such that the determined target vehicle        drive force permits a smooth change of an actual vehicle drive        force with a change of the operating amount of the vehicle        accelerating member, irrespective of a shifting action of the        transmission;    -   a first controlling portion having a relatively high operating        response and operable to effect a transient control of a torque        of the drive power source so that the actual vehicle drive force        coincides with the target vehicle drive force after the shifting        action of the transmission; and    -   a second controlling portion having lower operating response        than the first controlling portion but is capable of        continuously controlling the torque of the drive power source,        said second controlling portion being operable to effect a        continuous control of the torque of the drive power source        following the transient control by the first controlling        portion, so that the actual vehicle drive force coincides with        the target vehicle drive force after the shifting action of the        transmission.

In the vehicle control apparatus of the present invention constructed asdescribed above, the target-drive-force setting portion determines thetarget vehicle drive force on the basis of the operating amount of themanually operable vehicle accelerating member (e.g., an acceleratorpedal) and the presently selected position of the transmission, suchthat the determined target vehicle drive force permits a smooth changeof the actual vehicle drive force with an increase of the operatingamount of the vehicle accelerating member, irrespective of the shiftingaction of the transmission. Further, the first controlling portionhaving a relatively high operating response effects a temporary ortransient control of the torque of the drive power source(drive-power-source torque), and the second controlling portion capableof continuously controlling the drive-power-source torque effects thecontinuous control of the drive-power-source torque following thetransient control by the first controlling portion. In this arrangement,the output torque of the transmission is smoothly changed with a changeof the operating amount of the manually operable vehicle acceleratingmember, without an abrupt change of the output torque upon a shiftingaction of the transmission, so that an abrupt change of the vehicledrive force after the shifting action is prevented to improve thedrivability of the vehicle. The first and second controlling portionsinclude drive-power-source-torque control devices that are available onthe vehicle and need not be provided as control devices exclusivelydesigned for the purpose of controlling the drive-power-source torque,so as to permit a smooth change of the vehicle drive force upon ashifting action of the transmission.

Where the drive power source device includes at least one of an engineand an electric motor, the first controlling portion preferably includesat least one of an ignition-timing control device operable to effect anignition-timing control of adjusting an ignition timing of the engine,and an electric-motor-torque control device operable to effect anelectric-motor-torque control of controlling a torque of the electricmotor. Accordingly, the drive-power-source torque can be controlled withan excellent response characteristic.

The second controlling portion preferably includes at least one of anelectronic-throttle-valve control device operable to effect anelectronic-throttle-valve control of controlling an opening angle of anelectronically controlled throttle valve of the engine, asupercharging-pressure control device operable to effect asupercharging-pressure control of controlling a supercharging pressureof a supercharger of the engine, and a valve-device control deviceoperable to effect an engine-cylinder control of controlling the numberof operable cylinders of the engine. These devices are capable ofcontinuously controlling the drive-power-source torque for a relativelylong time.

In one preferred form of the invention, the vehicle control apparatusfurther comprises a shifting-completion determining portion operable todetermine whether the shifting action of the transmission is completed,and a transient-control-time-lapse determining portion operable todetermine whether a predetermined transient control time has passedafter a moment of determination by the shifting-completion determiningportion that the shifting action is completed. In this case, thetransient control of the torque of the drive power source by the firstcontrolling portion is effected for the predetermined transient time,and is switched to the continuous control by the second controllingportion at a moment of determination by the transient-control-time-lapsedetermining portion that the predetermined transient control time haspassed.

In one advantageous arrangement of the above-described preferred form ofthe invention, the shifting action of the transmission is shift-down,and the transient control of the torque of the drive power source by thefirst controlling portion is gradually switched to the continuouscontrol by the second controlling portion such that an amount of changeof the torque of the drive power source by the first controlling portionin a direction that permits the smooth change of the actual vehicledrive force is gradually increased while an amount of change of thetorque of the drive power source by the second controlling portion inthe above-indicated direction is gradually reduced.

In another preferred form of the invention, the vehicle controlapparatus further comprises a memory storing a data map representativeof a predetermined relationship among the target vehicle drive force,the operating amount of the manually operable vehicle acceleratingmember and the plurality of operating positions of the transmission, andwherein the target-drive-force setting portion determines the targetvehicle drive force on the basis of the operating amount of the manuallyoperable vehicle accelerating member and the presently selected positionof the transmission, and according to the predetermined relationshiprepresented by the data map stored in the memory.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, advantages and technical andindustrial significance of the present invention will be betterunderstood by reading the following detailed description of a preferredembodiment of the invention, when considered in connection with theaccompanying drawings, in which:

FIG. 1 is a schematic view showing a part of a drive system of a hybridvehicle, which is controlled by a control apparatus constructedaccording to one embodiment of this invention;

FIG. 2 is a table indicating a relationship between combinations ofoperating states of hydraulically operated frictional coupling devicesof an automatic transmission of the vehicle drive system shown in FIG.1, and operating positions of the automatic transmission to beestablished by the respective combinations of the operating states;

FIG. 3 is a schematic view showing various devices of the vehicle drivesystem of FIG. 1 including the engine and automatic transmission;

FIG. 4 is a view illustrating a variable valve mechanism provided foreach cylinder of the engine;

FIG. 5 is a view illustrating an arrangement of an electromagneticactuator system provided in the variable valve mechanism of FIG. 4, foropening and closing an intake valve or an exhaust valve at apredetermined timing;

FIG. 6 is a view for explaining input and output signals of anelectronic control device of the vehicle control apparatus for thevehicle drive system of FIG. 1:

FIG. 7 is a view indicating a relationship between an opening angle of athrottle valve of the engine and an operating amount of an acceleratorpedal, in the vehicle drive system controlled by the vehicle controlapparatus

FIG. 8 is a view indicating boundary lines used by the electroniccontrol unit to control shifting actions of the automatic transmissionof the vehicle drive system;

FIG. 9 is a view indicating a stored data map used by the electroniccontrol unit to calculate an estimated value of the engine torque on thebasis of the opening angle of the throttle valve and an operating speedof the engine;

FIG. 10 is a view showing a shifting device provided for shifting theautomatic transmission;

FIG. 11 is a block diagram showing major functional means of theelectronic control unit of FIG. 6;

FIG. 12 is a view indicating a relationship between a drive-power-sourcetorque in the form of the engine torque and an output torque of theautomatic transmission for each of third-speed, fourth-speed andfifth-speed positions of the automatic transmission in the drive systemof FIG. 1, and a relationship between the operating amount of theaccelerator pedal and a target value of the output torque of thetransmission;

FIG. 13 is a view indicating relationships between the output torque ofthe automatic transmission and the operating amount of the acceleratorpedal, wherein the relationship according to the present embodiment isindicated by solid line, while the relationship in the prior art isindicated by broken line;

FIG. 14 is a flow chart illustrating a drive-power-source-torque controlroutine executed by the electronic control unit shown of FIG. 6, forcontrolling a drive-power-source torque, so as to permit a smooth changeof the output torque of the automatic transmission with a change of theoperating amount of the accelerator pedal, upon a shifting action of thetransmission; and

FIG. 15 is a time chart indicating changes of various parameters duringan operation of the electronic control unit to control thedrive-power-engine torque according to the drive-power-source-torquecontrol routine of FIG. 14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to the schematic view of FIG. 1, there is shown anarrangement of a drive system 8 of a hybrid vehicle that is controlledby a vehicle control apparatus constructed according to one embodimentof this invention. The vehicle drive system 8 includes an internalcombustion engine 10, an input clutch 12, a fluid-operated powertransmitting device in the form of a torque converter 14, and anautomatic transmission 16. The engine 10 constitute a part of a drivepower source of the vehicle. An output of the engine 10 is transmittedto the automatic transmission 16 through the input clutch 12 and torqueconverter 14, and is transmitted from the automatic transmission 16 todrive wheels through a differential gear device and drive axles, whichare well known in the art and are not shown. Between the input clutch 12and the torque converter 14, there is disposed the above-described firstmotor/generator MG1, which functions as an electric motor and anelectric generator.

The torque converter 14 includes: a pump impeller 20 connected to theinput clutch 12; a turbine impeller 24 connected to an input shaft 22 ofthe automatic transmission 16; a lock-up clutch 26 for directlyconnecting the pump and turbine impellers 20, 24; a one-way clutch 28;and a stator impeller 30 which is prevented by the one-way clutch 28from rotating in one of opposite directions.

The lock-up clutch 26 is a hydraulically operated friction clutch whichhas an engaging chamber 25 and a releasing chamber 27 and which isengaged in the presence of a difference ΔP between two fluid pressuresin the respective engaging and releasing chambers 25, 37. When thelock-up clutch 26 is placed in its fully engaged state, the pump andturbine impellers 20, 24 are rotated as a unit. When the lock-up clutch26 is in a partially slipping state with the pressure difference ΔPbeing feed-back controlled to adjust its engaging torque, the turbineimpeller 24 is rotated by the pump impeller 20 such that the rotatingspeed of the turbine impeller 24 is lower than that of the pump impeller20 by a predetermined target slip speed (for example, 50 r.p.m.), whenthe vehicle is driven by an output of the engine 10, for example. Whenthe vehicle is driven by a kinetic energy of the vehicle in a runningstate with the engine 10 kept in an off state, for example, the pumpimpeller 20 is rotated by the turbine impeller 24 such that the rotatingspeed of the pump impeller 20 is lower than that of the turbine impeller24 by the predetermined target slip speed (e.g., 50 r.p.m.).

The automatic transmission 16 has a plurality of operating positionshaving respective speed ratios and is placed in a selected one of theoperating positions, as described below. The automatic transmission 16includes a first transmission unit 32 having two speed positions, thatis, a high-speed position and a low-speed position, and a secondtransmission unit 34 having six operating positions, that is, onereverse drive position and five forward drive positions. The firsttransmission unit 32 includes a high-low switching planetary gear device36 having a sun gear S0, a ring gear R0, a carrier K0, and planetarygears P0 which are rotatably supported by the carrier K0 and which meshwith the sun gear S0 and ring gear R0. The first transmission unit 32further includes a clutch C0 and a one-way clutch F0 disposed betweenthe sun gear S0 and the carrier K0, and a brake B0 disposed between thesun gear S0 and a housing 38.

The second transmission unit 34 includes a first planetary gear set 40,a second planetary gear set 42, and a third planetary gear set 44. Thefirst planetary gear set 40 includes a sun gear S1, a ring gear R1, acarrier K1, and planetary gears P1 which are rotatably supported by thecarrier K1 and which mesh with the sun gear S1 and ring gear R1. Thesecond planetary gear set 42 includes a sun gear S2, a ring gear R2, acarrier K2, and planetary gears P2 which are rotatably supported by thecarrier K2 and which mesh with the sun gear S2 and ring gear R2. Thethird planetary gear set 44 includes a sung gear S3, a ring gear R3, acarrier K3, and planetary gears P3 which are rotatably supported by thecarrier K3 and which mesh with the sun gear S3 and ring gear R3.

The sun gears S1 and S2 are integrally connected to each other, whilethe ring gear R1 and carriers K1 and K2 are integrally connected to eachother. The carrier K3 is connected to an output shaft 46 of theautomatic transmission 16. A clutch C1 is disposed between the ring gearR0 and an intermediate shaft 48 connected to the sun gear S3, while aclutch C2 is disposed between the sun gears S1 and S2 and the ring gearR0. A brake B1 of band type for inhibiting rotation of the sun gears S1and S2 is fixed to the housing 38. A one-way clutch F1 and a brake B2are disposed in series with each other between the sun gears S1 and S2and the housing 38. This one-way clutch F1 is engaged when the sun gearsS1 and S2 receive a torque so as to be rotated in a direction oppositeto the direction of rotation of the input shaft 22.

A brake B3 is disposed between the carrier K1 and the housing 38, whilea brake B4 and a one-way clutch F2 are disposed in parallel with eachother between the ring gear R3 and the housing 38. This one-way clutchF2 is engaged when the ring gear R3 receives a torque so as to berotated in the direction opposite to the direction of rotation of theinput shaft 22.

The automatic transmission 16 constructed as described above has onereverse drive position and five forward drive positions, which areselectively established by engagement of respective combinations offrictional coupling devices in the form of the clutches C0–C2, brakesB0–B4 and one-way clutches F0–F2, as indicated in the table of FIG. 2 byway of example. In FIG. 2, “◯” indicates the engaged state of eachfrictional coupling device, and the absence of any symbol indicates thereleased state of each frictional coupling device. “⊚” indicates theengagement of the appropriate frictional coupling device for applying anengine brake to the vehicle, and “Δ” indicates the engagement of theappropriate frictional coupling device, which does not contribute totransmission of power. It will be understood from the table of FIG. 2that a 2–3 shift-up action of the automatic transmission 16 from a2^(nd)-speed position to a 3^(rd)-speed position is a so-called“clutch-to-clutch” shifting action which is effected by an engagingaction of the brake B2 and a releasing action of the brake B3 which takeplace concurrently with each other. A 3–2 shift-down action of theautomatic transmission 16 from the 3^(rd)-speed position to the2^(nd)-speed position is also a “clutch-to-clutch” shifting action whichis effected by an engaging action of the brake B3 and a releasing actionof the brake B2 which take place concurrently with each other.

The engine 10 is provided with a supercharger 54 of exhaust turbochargertype having a pump impeller 51 disposed in an intake pipe 50, and aturbine impeller 53 disposed in an exhaust pipe 52, as shown in FIG. 3.The turbine impeller 53 is rotated by a stream of an exhaust gas oremission from the engine 10 through the exhaust pipe 52, and the pumpimpeller 51 is connected to the turbine impeller 53 and is rotated bythe turbine impeller 53 to compress an intake air to be introduced intothe engine 10. A by-pass passage 58 which by-passes the turbine impeller53 is connected to the exhaust pipe 52 such that the by-pass-passage 58is disposed in parallel with a portion of the exhaust pipe 52 in whichthe turbine impeller 53 is provided. The by-pass passage 58 is providedwith an exhaust waste gate valve 56 which is controlled to change aratio of a volume of the exhaust emission flowing to drive the turbineimpeller 53, to a volume of the exhaust emission flowing through theby-pass passage 58, for thereby adjusting a supercharging pressure Pawithin the intake pipe 50.

The supercharger 54 of exhaust turbocharger type may be replaced orassisted by a supercharger of mechanical type driven by the engine 10 oran electric motor. An electronically controlled throttle valve 62 isalso disposed within the intake pipe 50 of the engine 10. The throttlevalve 62 is operated by a throttle actuator 60 such that an angle ofopening θ_(TH) of the throttle valve 62 is in principle controlled to avalue corresponding to an operating amount Acc of a manually operatedvehicle accelerating member in the form of an accelerator pedal 88 (FIG.11), which operating amount Acc represents an output of the vehicledrive system 8 as required by an operator of the vehicle.

As shown in FIG. 4, the engine 10 is provided with a variable valvemechanism 78 and a valve drive control device 81. The variable valvemechanism 78 includes an electric actuator in the form of anelectromagnetic actuator 76 for opening and closing the intake valve 74of each cylinder of the engine 10, and an electric actuator in the formof an electromagnetic actuator 77 for opening and closing the exhaustvalve 75 of each cylinder. The valve drive control device 81 is arrangedto control the timings and periods of opening and closing actions andlift amounts of the intake and exhaust valves 74, 75, according to anoutput signal of an angular position sensor 80 for detecting an angularposition of a crankshaft 79 of the engine 10. The valve drive controldevice 81 not only optimizes the opening and closing timings of theintake and exhaust valves 74, 75 depending upon a load acting on theengine 10, but also adjusts the opening and closing timings to beadapted to one of a 4-cycle operating mode and a 2-cycle operating modewhich is selected according to a mode selecting signal. The engine 10has a function of controlling its speed N_(E), with the valve drivecontrol device 81 which permits the adjustment of the operating timingsof the intake and exhaust valves 74, 75 of the variable valve mechanism78 and the selection of the number of the operating cylinders. Forexample, the opening and closing actions of the exhaust valve 74 arecontrolled with the intake valve 74 kept closed, so that a rotary motionof the engine 10 is consumed by a resistance to the rotary motion, whichis generated in the compression stroke of the piston, whereby theoperating speed N_(E) of the engine 10 can be positively or rapidlyreduced. Further the opening angle of the intake valve 74 is controlledto adjust a rate of change of the engine speed N_(E).

As shown in FIG. 5, each of the electromagnetic actuators 76, 77includes a circular disc-like movable member 82 made of a magneticmaterial, which is connected to the intake or exhaust valve 74, 75 suchthat the movable member is movable in the axial direction of the valve74, 75. The electromagnetic actuator 76, 77 further includes a pair ofelectromagnets 84, 85 disposed on the respective opposite sides of themovable member 82, and a pair of springs 86, 87 biasing the movablemember 82 to its neutral position between the two electromagnets 84, 85.The movable member 82 is attracted by one of the two electromagnets 84,85. The intake valve 74 and exhaust valve 75 are electrically operatedshut-off valves whose opening and closing actions are electricallycontrollable.

As also shown in FIG. 3, the first motor/generator MG1 described aboveis disposed between the engine 10 and the automatic transmission 16,such that the clutch 12 is disposed between the engine 10 and the firstmotor/generator MG1. The vehicle drive system 8 further includes ahydraulic control unit 66 which receives a pressurized fluid (linepressure) from a mechanical oil pump 68 and which controls thehydraulically operated frictional coupling devices of the automatictransmission 16 and the lock-up clutch 26. The mechanical oil pump 68 ismechanically connected to and directly driven by the engine 10 throughan electrically operated hydraulic pump or an oil pump clutch 69 (shownin FIG. 1). The pressure of the pressurized fluid received by thehydraulic control unit 66 is high enough to place the hydraulicallyoperated frictional coupling devices in their fully engaged states.

A second motor/generator MG2 is operatively connected to the engine 10,as indicated in FIG. 3. The second motor/generator MG functions as anelectric drive motor and an electric generator. The firstmotor/generator MG1 and the second motor/generator MG2 function as anassisting drive device which assists the engine 10 to drive the vehicle,and cooperate with the engine 10 to constitute the drive power sourcefor the vehicle. The vehicle drive system 8 further includes a fuel cell70 and a secondary battery 71 which serve as an electric power sourcefor the first motor/generator MG1 and the second motor/generator MG2,and also includes two switching devices 72, 73 which are arranged tocontrol the amounts of electric current to be applied from the fuel cell70 and the secondary battery 71 to the motor/generator MG1 andmotor/generator MG2 when serving as the electric motors, and the amountsof electric current with which the secondary battery 71 is charged bythe motor/generator MG1 and motor/generator MG2 when serving as theelectric generators. Each of the switching devices 72, 73 is a devicecapable of performing a switching function, for instance, asemiconductor switching element capable of serving as an inverter.

The vehicle drive system 8 described above is controlled by theabove-indicated electronic control unit (ECU) 90, the input and outputsignals of which are indicated in FIG. 6. The electronic control unit 90receives as its input signals the following output signals of varioussensors (not shown): an accelerator signal indicative of the operatingamount Acc of the accelerator pedal 88 detected by an accelerator sensor89 (FIG. 11); a throttle opening angle signal indicative of the openingangle θ_(TH) of the throttle valve 62 detected by a throttle openingsensor 63 (FIG. 3); a vehicle speed signal indicative of a rotatingspeed N_(OUT) of the output shaft 46 of the automatic transmission 16which is detected by an output-shaft-speed sensor 47 (FIG. 1) and whichcan be used to detect a running speed V of the vehicle; a turbine speedsignal indicative of a rotating speed N_(T) of the turbine impeller 24(rotating speed N_(IN) of the input shaft 22) detected by aturbine-speed sensor (not shown); an engine speed signal indicative ofthe operating speed N_(E) of the engine 10 detected by an engine-speedsensor 99 (FIG. 1); a signal indicative of the supercharging pressure Pain the intake pipe 50; a signal indicative of an air/fuel ratio A/F ofan air-fuel mixture supplied to the engine 10; a signal indicative of apresently selected operating position P_(SH) of a shift lever 92 (FIG.11) detected by a shift-position detector 98 (FIG. 10); and a signalindicative of a temperature T_(OIL) of working fluid used for theautomatic transmission 16.

The electronic control unit 90 generates the following output signals: athrottle actuator drive signal for controlling the throttle actuator 60to operate the throttle valve 62, for establishing the throttle openingangle θ_(TH) corresponding to the operating amount Acc of theaccelerator pedal 88; a fuel injection signal for controlling an amountof fuel to be injected from a fuel injector valve (not shown) into eachcylinder of the engine 10; solenoid drive signals S1, S2 and S3 forcontrolling solenoid coils for driving shift control valves incorporatedin the hydraulic control unit 66, to shift the automatic transmission 16as needed; a drive signal D_(SLT) for controlling a linear solenoidvalve SLT to control the line pressure for controlling theclutch-to-clutch shifting actions of the automatic transmission 16; adrive signal D_(SLU) for controlling a linear solenoid valve SLU tocontrol engaging, releasing and slipping actions of the lock-up clutch26; a drive signal D_(SLN) for controlling a linear solenoid valve SLNto control a back pressure of an accumulator.

The electronic control unit 90 includes a so-called microcomputerincorporating a central processing unit (CPU), a read-only memory (ROM),a random-access memory (RAM), and an input-output interface. The CPUoperates to effect signal processing operations according to controlprograms stored in the ROM, while utilizing a temporary data storagefunction of the RAM, for executing various control routines such as: athrottle valve control routine for controlling the opening angle θ_(TH)(%) of the throttle valve 56; a transmission shift control routine forcontrolling the shifting actions of the automatic transmission 26; alock-up clutch control routine for controlling the engaging, releasingand slipping actions of the lock-up clutch 26; a supercharging pressurecontrol routine for controlling the supercharging pressure Pa within theintake pipe 50 ; an air/fuel ratio control routine for controlling theair/fuel ratio A/F of the engine 10: a cylinder-number selecting controlroutine for changing the number of the operating cylinders of the engine10; and a mode selecting control routine for selecting one of the2-cycle and 4-cycle operating modes.

For instance, the output of the engine 10 is controlled by controllingthe throttle actuator 50 to control the opening and closing actions ofthe throttle valve 62, controlling the fuel injector valve to controlthe amount of the fuel to be injected into the engine 10, andcontrolling an ignition device 59 (FIG. 33) such as an igniter. Theopening angle θ_(TH) of the throttle valve 62 is controlled by drivingthe throttle actuator 60 on the basis of the detected operating amountAcc (%) of the manually operated vehicle accelerating member in the formof the accelerator pedal 88, and according to a predeterminedrelationship between the opening angle θ_(TH) and operating amount Acc,as indicated in the graph of FIG. 7, by way of example, such that theopening angle θ_(TH) of the throttle valve 62 increases with an increasein the operating amount Acc of the accelerator pedal 88.

The transmission shift control routine is formulated to effect adetermination as to whether the automatic transmission 16 should beshifted down or up, on the basis of the detected operating amount Acc(%) of the accelerator pedal 88 or opening angle θ_(TH) of the throttlevalve 62 and the detected vehicle running speed V (km/h), and accordingto predetermined shift-down and shift-up boundary lines represented by adata map stored in the ROM, as shown in FIG. 8. When any shift-up orshift-down action of the automatic transmission 16 is determined to berequired, the solenoid coils of the shift control valves in thehydraulic control circuit 66 are controlled to effect the requiredshift-up or shift-down action. Namely, the determination is made as towhether a point defined by the detected operating amount Acc or throttleopening angle θ_(TH) and the detected vehicle running speed V has movedacross f the throttle valve 62 has moved across any one of the shift-upand shift-down boundary lines. In the transmission shift control, aninput torque T_(IN) of the automatic transmission 16 is estimated, andthe hydraulic engaging pressure of the hydraulically operated frictionalcoupling device which is engaged to effect the shifting action, or theline pressure for this hydraulic engaging pressure is adjusted to avalue corresponding to the estimated input torque T_(IN). Further, atorque T_(E) of the engine 10 which is transmitted to the automatictransmission 16 through the lock-up clutch 26 and which gives the inputtorque T_(IN) is calculated as an estimated engine torque T_(EO) on thebasis of the detected engine speed N_(E) and the required output of thedrive power source as represented by the detected opening angle θ_(TH)of the throttle valve 62, for example, and according to a predeterminedrelationship among the detected engine speed N_(E) and throttle openingangle θ_(TH) and the estimated engine torque T_(EO), as indicated inFIG. 9 by way of example. This predetermined relationship is alsorepresented by a data map stored in the ROM.

As shown in FIG. 10, a manually operated shift-position selecting devicein the form of a shifting device 94 includes the shift lever 92indicated above and is located near an operator's seat provided in thevehicle. The shift lever 92 has the following operating positions: aparking position P for locking the output shaft 46 of the automatictransmission 16; a reverse drive position R for reverse running of thevehicle; a neutral position N in which a power transmitting path throughthe automatic transmission 16 is disconnected; a forward drive positionD (highest-speed position) in which the automatic transmission 16 isshiftable to a selected one of 1^(st)-speed, 2^(nd)-speed, 3^(rd)-speed,4^(th)-speed and 5^(th)-speed positions in an automatic shifting mode; afourth engine-braking drive position 4 in which the automatictransmission 16 is shiftable to a selected one of the 1^(st)-speedthrough 4^(th)-speed positions in the automatic shifting mode and anengine brake is applied to the vehicle in the selected speed position; athird engine-braking drive position 3 in which the automatictransmission 16 is shiftable to a selected one of the 1^(st)-speedthrough 3^(rd)-speed positions in the automatic shifting mode and theengine brake is applied to the vehicle in the selected speed position; asecond engine-braking drive position 2 in which the automatictransmission 16 is shiftable to a selected one of the 1^(st)-speed and2^(nd)-speed positions in the automatic shifting mode and the enginebrake is applied to the vehicle in the selected 1^(st)-speed or2^(nd)-speed position; and a first engine-braking drive position L inwhich the automatic transmission 16 is placed in the 1^(st)-speedposition and the engine brake is applied to the vehicle with thetransmission 16 placed in the 1^(st)-speed position.

The parking position P and the neutral position N are non-drivepositions in which the vehicle is not driven, and the reverse driveposition R is a reverse running position for driving the vehicle in thereverse direction, while the forward drive position D and the fourth,third, second and first engine-braking drive positions 4, 3, 2, L areall forward running positions for driving the vehicle in the forwarddirection. The forward drive position D is a highest-speed runningposition or non-engine-braking running position in which the vehicle canbe driven at a highest speed, and the engine-braking drive positions 4,3, 2 and L are selected to drive the vehicle with larger drive forces,and are engine-braking positions in which the engine braking is appliedto the vehicle while the vehicle is driven with a kinetic energy. Toplace the automatic transmission 16 in the 2^(nd)-speed positionindicated in FIG. 2 while the shift lever 94 is placed in thenon-engine-braking forward drive position D, the clutch C1 and the brakeB3 are engaged. While the shift lever 94 is placed in the secondengine-braking position 2, on the other hand, the clutch C0 as well asthe clutch C1 and brake B3 is engaged to place the automatictransmission 16 in the 2^(nd)-speed position.

As shown in FIG. 10, the shifting device 94 further includes a modeselector switch 96 used to select a SPORTY mode for sporty running ofthe vehicle, and a MANUAL SHIFT mode in which the automatic transmission16 can be manually shifted by using manual shift-down and shift-uppushbuttons (not shown) provided on a steering wheel of the vehicle.

Referring next to the block diagram of FIG. 11, there are illustratedmajor functional means of the electronic control unit 90, which includea shift control portion 100, a shifting-completion determining portion102, a drive-power-source-torque control portion 104, atarget-drive-force setting portion 106, a vehicle-state detectingportion 108; and a transient-control-time lapse determining portion 114.The shift control portion 100 is arranged to select one of the operatingpositions of the automatic transmission 16, on the basis of the detectedopening angle θ_(TH) of the throttle valve 62 and vehicle running speedV, and according to the shift-up and shift-down boundary lines which arerepresented by the stored data map and defined in a two-dimensionalcoordinate system, as shown in FIG. 8, as described above. The shiftcontrol portion 100 is further arranged to command the hydraulic controlunit 66, for placing the hydraulically operated frictional couplingdevices C, B, F in the engaged or released positions to place theautomatic transmission 16 in the selected position.

A shifting action of the automatic transmission 16 to the selectedposition under the control of the shift control portion 100 causes achange in an output torque T_(OUT) of the automatic transmission 16.Where the automatic transmission 16 is shifted down from the4^(th)-speed position to the 3^(rd)-speed position, for example, thisshift-down action causes an increase in the output torque T_(OUT) of theautomatic transmission 16 from a 4^(th)-speed torque value T_(OUT4) to a3^(rd)-speed torque value T_(OUT3). A ratio of the 3^(rd)-speed torquevalue T_(OUT3) to the 4^(th)-speed torque value T_(OUT4) is equal to aratio of a speed ratio γ3 of the 3^(rd)-speed position to a speed ratioγ4 of the 4^(th)-speed position. Namely, T_(OUT3)=γ3/γ4·T_(OUT4).Accordingly, a vehicle drive force F which is proportional to the outputtorque T_(OUT) of the automatic transmission 16 changes before and afterthe automatic transmission 16 is shifted to the newly selected position.This change of the vehicle drive force F may cause a shifting shock anddeteriorate the drivability of the vehicle. The vehicle drive force F iscalculated on the basis of the output torque T_(OUT) of the automatictransmission 16, and related parameters such as a speed reduction ratioand power transmission loss between the output shaft 46 and the vehicledriving wheels, and a diameter of the driving wheels. In this sense, thevehicle drive force F and the output torque T_(OUT) of the automatictransmission T_(OUT) may be considered to be substantially equivalent toeach other.

The vehicle-state detecting portion 108 is arranged to read in theoutput signals of the various sensors which indicate the present runningstate of the vehicle. For instance, the vehicle-state detecting portion108 reads in the engine speed N_(E) detected by the engine speed sensor99, the turbine speed N_(T) (speed N_(IN) of the input shaft 22)detected by the turbine speed sensor 91, the vehicle running speed V(speed N_(OUT) of the output shaft 46) detected by theoutput-shaft-speed sensor 47, the opening angle θ_(TH) of the throttlevalve 62 detected by the throttle opening sensor 62, the operatingamount Acc of the accelerator pedal 88 detected by the acceleratorsensor 98, and the selected position P_(SH) of the shift lever 92detected by the shift-position detector 98. On the basis of those kindsof detected information, the vehicle-state detecting portion 108determines whether the vehicle is in a running state or not. Further,the vehicle-state detecting portion 108 determines the presentlyselected operating position of the automatic transmission 16, on thebasis of a command generated by the shift control portion 100 to shiftthe automatic transmission 16 according to the shift-up and shift-downboundary lines of FIG. 8.

The target-drive-force setting portion 106 is arranged to determine atarget output torque T_(OUT)* of the automatic transmission 16corresponding to a target vehicle drive force F*, on the basis of thedetected operating amount Acc of the accelerator pedal 88 and thepresently selected position of the automatic transmission 16. Thistarget output torque T_(OUT)* is determined so as to permit a smoothchange of (increase) of the actual output torque T_(OUT) of theautomatic transmission 16 with a change (increase) of the operatingamount Acc of the accelerator pedal 88, irrespective of a shiftingaction (e.g., shift-down action) of the automatic transmission 16. FIG.12 indicates an example of a relationship between a drive-power-sourcetorque (as represented by the detected operating amount Acc of theaccelerator pedal 88) and the output torque T_(OUT) of the automatictransmission for each of the 3^(rd)-speed, 4^(th)-speed and 5^(th)-speedpositions of the automatic transmission 16. It will be understood fromFIG. 12 that the output torque T^(OUT) of the automatic transmission 16for a given value of the drive-power-source torque increases in steps asthe automatic transmission 16 is shifted down from the 5^(th)-speedposition toward the 3^(rd)-speed position. Accordingly, there is apossibility of deterioration of the drivability of the vehicle due to achange of the output torque T_(OUT) before and after a shifting actionof the automatic transmission 16.

To minimize the above-indicted possibility of deterioration of thevehicle drivability, the target-drive-force setting portion 106 isarranged to determine the target output torque T_(OUT)* of the automatictransmission 16, so as to reduce an amount of change of the outputtorque T_(OUT) of the automatic transmission 16 before and after ashift-down action, for thereby permitting a smooth increase of theoutput torque T_(OUT) of the automatic transmission 16 with an increaseof the operating amount Acc of the accelerator pedal 88 upon theshift-down action of the automatic transmission 16. That is, the targetoutput torque T_(OUT)* is determined to permit a smooth increase of theoutput torque T_(OUT) from a value before the shift-down action to avalue after the completion of the shift-down action of the transmission16, when the shift-down action takes place as a result of increase ofthe operating amount Acc of the accelerator pedal 88. Thick solid linein FIG. 12 indicates an example of a predetermined pattern of increasein the target output torque T_(OUT)* of the automatic transmission 16when the automatic transmission 16 is shifted down from the 5^(th)-speedposition to the 4^(th)-speed position, and from the 4^(th)-speedposition to the 3^(rd)-speed position, as a result of an increase in theoperating amount Acc of the accelerator pedal 88. This pattern ofincrease in the target output torque T_(OUT)* is represented by a datamap stored in the ROM of the electronic control unit 90. Thetarget-drive-force setting portion 106 determines the target outputtorque T_(OUT)*, on the basis of the presently selected operatingposition of the automatic transmission 16 and the detected operatingamount Acc of the accelerator pedal 88, and according to thepredetermined pattern of increase of the target output torque T_(OUT)*in relation to the selected operating position of the automatictransmission 16 and the operating amount Acc (%) of the acceleratorpedal 88. With the target output torque T_(OUT)* being thus determined,the actual output torque T_(OUT) does not increase in steps or at a highrate, but increases smoothly or at a relatively low rate with anincrease of the drive-power-source torque as represented by theoperating amount Acc of the accelerator pedal 88, irrespective of theshift-down action from the 5^(th)-speed position to the 4^(th)-speedposition or from the 4^(th)-speed position to the 3^(rd)-speed position.For example, the thick solid line indicates a relatively small amount ofincrease of the actual output torque T_(OUT) corresponding to anincrease of the operating amount Acc from the 40% value to the 50%value.

The shifting-completion determining portion 102 is arranged to determinewhether a shifting action of the automatic transmission 100 under thecontrol of the shift control portion 100 is terminated or completed. Thedetermination that the shifting action is completed is made bydetermining whether the speed N_(IN) of the input shaft 22 which followsthe engine speed N_(E) via the torque converter 14 has becomesubstantially equal to a synchronizing input shaft speed (γ×N_(OUT)),which is a product of the speed N_(OUT) of the output shaft 46 and thespeed ratio γ of the automatic transmission 16 after completion of theshifting action. This determination by the shifting-completiondetermining portion 102 is used to initiate a transient drive forcecontrol by a first controlling portion 110 of thedrive-power-source-torque control portion 104 which will be described.

The drive-power-source-torque control portion 104 includes theabove-indicated first controlling portion 110 and a second controllingportion 112, and is arranged to control the drive power source in theform of the engine 10, motor/generator MG1 and motor/generator MG2, suchthat the drive power source produces a torque T_(PD) which permits theactual output torque T_(OUT) of the automatic transmission 16 tocoincide with the target output T_(OUT)* determined by thetarget-drive-force setting portion 106 described above. In this respect,it is noted that the output torque T_(OUT) of the automatic transmission16 having the plurality of operating positions having the respectivedifferent speed ratios considerably changes from a value before ashifting action to a value after completion of the shifting action.Accordingly, the drive-power-source torque T_(PD) must be controlled toreduce an amount of change of the output torque T_(OUT) of the automatictransmission 16 before and after the shifting action. To this end, thefirst controlling portion 110 which has a higher operating response thanthe second controlling portion 112 is operated to initiate a temporarycontrol of the drive-power-source torque T_(PD), upon determination bythe shifting-completion determining portion 102 that the shifting actionof the automatic transmission 16 is completed. The temporary control ofthe drive-power-source torque T_(PD) by the first controlling portion110 is effected such that the actual output torque T_(OUT) coincideswith the target output torque T_(OUT)*. The temporary control by thefirst controlling portion 110 is followed by a continuous control of thedrive-power-source torque T_(PD) by the second controlling portion 112,which has a lower operating response but is capable of continuouslycontrolling the drive-power-source torque T_(PD). For example, ashift-down action of the automatic transmission 16 results in aconsiderable increase of the output torque T_(OUT), so that thedrive-power-source torque T_(PD) must be reduced. To this end, thetemporary control by the first controlling portion 110 having arelatively high operating response is initiated to temporarily reducethe drive-power-source torque T_(PD), upon determination of completionof the shifting action by the shifting-completion determining portion102, and then the continuous control by the second controlling portion112 is effected following the temporary control, for continuouslyreducing the drive-power-source torque T_(PD).

The temporary control of the drive-power-source torque T_(PD) by thefirst controlling portion 110 is effected for a predetermined transientcontrol time t_(P) after the moment of completion of the shifting actionof the automatic transmission 16. During this control time t_(P), thesecond controlling portion 112 is not highly responsive to a signalgenerated by the shifting-completion determining portion 102, and is nothighly capable of timely controlling the drive-power-source torqueT_(PD), for reducing the amount of change of the output torque T_(OUT)of the automatic transmission 16 without a delay. In this respect, thetemporary control of the drive-power-source torque T_(PD) by the firstcontrolling portion 110 may be referred to as a “transient drive forcecontrol”.

The first controlling portion 110 is suitable for effecting thetemporary control of the drive-power-source torque T_(PD). Namely, thefirst controlling portion 110 has a sufficiently high operating responsebut is not highly capable of effecting the continuous control of thetorque T_(PD), as already indicated above. For instance, this firstcontrolling portion 110 includes at least one of an ignition-timingcontrol device and an electric-motor-torque control device. Theignition-timing control device is arranged to effect an ignition-timingcontrol of adjusting or changing (retarding) an ignition timing of theengine 10 by controlling the ignition device 59. Theelectric-motor-torque control device is arranged to effect anelectric-motor-torque control of controlling an electric motor torqueT_(M) by controlling the switching devices 72, 73 to control amounts ofelectric current to be applied from the fuel cell 70 and the secondarybattery 71 to the first motor/generator MG1 and/or the secondmotor/generator MG2. The electric motor torque T_(M) is a total torqueof the motor/generator MG1 and the motor/generator MG2. Thedrive-power-source torque T_(PD) is equal to a sum of the engine torqueT_(E) and the electric motor torque T_(M). However, the ignition-timingcontrol by the ignition-timing control device is not suitable to controlthe engine torque T_(E) before the engine 10 is sufficiently warmed up,and may not be continued for a long time since an exhaust emission fromthe engine 10 may be deteriorated by a long period of the ignitiontiming control. On the other hand, the electric-motor-torque control bythe electric-motor-torque control device may not be continued for a longtime under some conditions of the fuel cell 70 and the secondary battery71. Thus, the ignition-timing control and the electric-motor-torquecontrol by the first controlling portion 110 are suitable fortemporarily controlling the drive-power-source torque T_(PD) for thetransient control time t_(P), with a sufficiently high response.

The second controlling portion 112 has a lower operating response but iscapable of continuously controlling the drive-power-source torque T_(PD)with high stability for a relatively long time. When the output torqueT_(OUT) of the automatic transmission 16 abruptly changes by arelatively large amount upon a shifting action thereof, the secondcontrolling portion 112 does not permit a timely control of thedrive-power-source torque T_(PD), so that the temporary or transientcontrol of the torque T_(PD) by the first controlling portion 110 isfirst initiated, and the temporary control is switched to thecontinuously control of the torque T_(PD) by the second controllingportion 112 when the predetermined transient control time t_(P) haspassed. At the time of expiration of the transient control time t_(P),the second controlling portion 112 is able to reduce thedrive-power-source torque T_(PD), and the amount of reduction of thetorque T_(PD) by the second controlling portion 112 is graduallyincreased. After the expiration of the transient control time tP, theamount of reduction of the torque T_(PD) by the temporary control by thefirst controlling portion 110 is gradually reduced as the amount ofreduction of the torque T_(PD) is gradually increased.

For example, the second controlling portion 112 suitable forcontinuously controlling the drive-power-source torque T_(E) includes atleast one an electronic-throttle-valve control device, asupercharging-pressure control device and the above-described valvedrive control device 81. The electronic-throttle-valve control device isarranged to effect an electronic-throttle-valve control of controllingthe throttle actuator 60 to control the opening angle θ_(TH) of theelectronically controlled throttle valve 62. The supercharging-pressurecontrol device is arranged to effect a supercharging-pressure control ofcontrolling the exhaust waste gate valve 56 to control the superchargingpressure of the supercharger 54 of exhaust turbocharger type. The valvedrive control device 81 is arranged to effect an engine-cylinder controlof controlling the number of the operable cylinders of the engine 10.For example, the electronic-throttle-valve control is formulated suchthat the opening angle θ_(TH) of the throttle valve 62 is controlledirrespective of the predetermined relationship of FIG. 7 between thisopening angle θ_(TH) and the operating amount Acc of the acceleratorpedal 88, so as to change the engine torque T_(E) for thereby changingthe output torque T_(OUT) of the automatic transmission 16. However, theelectronic-throttle-valve control device does not have a sufficientlyhigh operating response, since the electronically controlled throttlevalve 62 does not have a high operating response, and since a surge tankis provided in an intake air passage.

When the accelerator pedal 88 is depressed to gradually increase itsoperating amount Acc, as indicated by thick solid line in FIG. 12, theautomatic transmission 16 is shifted down from the 4^(th)-speed positionto the 3^(rd)-speed position in the process of change of the operatingamount Acc from 60% to 70%, for example. In this case, the transientcontrol of the drive-power-source torque T_(PD) by the first controllingportion 110 of the drive-power-source-torque control portion 104 iseffected for the predetermined transient control time t_(P) aftercompletion of the shift-down action, to temporarily reduce thedrive-power-source torque T_(PD), for reducing the output torque T_(OUT)of the automatic transmission 16 such that the reduced output torqueT_(OUT) coincides with the target output torque TOUT* determined whenthe shift-down action takes place. During the transient control timet_(P), the drive-power-source torque T_(PD) can be effectively reducedwithout a delay, by the first controlling portion 110 having acomparatively high operating response. For example, the temporary ortransient control of the drive-power-source torque T_(PD) is effected byretarding the ignition timing of the engine 10 by operation of theignition-timing control device, and/or by controlling the amount ofelectric current to be applied to the first motor generator MG1 and/orthe second motor generator MG1.

Upon expiration of the transient control time t_(P), the secondcontrolling portion 112 is able to reduce the drive-power-source torqueT_(PD), and the amount of reduction of the torque T_(PD) by the secondcontrolling portion 112 is gradually increased. After the expiration ofthe transient control time tP, the amount of reduction of the torqueT_(PD) by the temporary control by the first controlling portion 110 isgradually reduced as the amount of reduction of the torque T_(PD) by thesecond controlling portion 112 is gradually increased. Thus, thetransient control by the first controlling portion 110 is graduallyswitched to the continuous control by the second controlling portion112. For example, the drive-power-source torque T_(PD) is reduced by thesecond controlling portion 112, by effecting at least one of (1) theelectronic-throttle-valve control to reduce the opening angle θ_(TH) ofthe electronically controlled throttle valve 62 by reducing the intakeair quantity to be introduced into the cylinders of the engine 10, (2)the supercharging-pressure control to lower the supercharging pressureof the supercharger 54, and (3) the engine-cylinder control to reducethe number of the operable cylinders of the engine 10. As a result, theoutput torque T_(OUT) of the automatic transmission 16 is smoothlychanged with a gradual increase of the operating amount Acc of theaccelerator pedal 88, as indicated by solid line in FIG. 13, so that anamount of change of the vehicle drive force before and after theshifting action of the automatic transmission 16 is effectively reducedto minimize a shifting shock of the automatic transmission 16, wherebythe drivability of the vehicle is improved. In FIG. 13, broken lineindicates a non-smooth or abrupt change of the output torque T_(OUT) ofan automatic transmission of a vehicle provided with the conventionalvehicle control apparatus.

The transient-control-time-lapse determining portion 114 is arranged todetermine whether the predetermined transient control time t_(P) haselapsed. As explained above, the transient control time t_(P) is aperiod of time in which the second controlling portion 112 is not highlyresponsive to the signal generated by the shifting-completiondetermining portion 102, and is not highly capable of timely controllingthe drive-power-source torque T_(PD), for reducing the amount of changeof the output torque T_(OUT) of the automatic transmission 16 without adelay. In other words, the operation of the second controlling portion112 becomes effective to reduce the amount of change of the outputtorque T_(OUT), when the predetermined transient control time t_(P) haspassed after the moment of completion of the shifting action of theautomatic transmission 16, which is detected by the shifting-completiondetermining portion 102. The transient control time t_(P) is determinedby a response delay time of the second controlling portion 112 which isobtained by laboratory experimentation or on the basis of data obtainedduring running of the vehicle.

Referring to the flow chart of FIG. 14, there is illustrated a routinefor controlling the drive-power-source torque T_(PD), which is executedby the electronic control unit 90 to permit a smooth change of theoutput torque T_(OUT) of the automatic transmission 16 with a continuouschange of the manually operated vehicle accelerating member in the formof the operating amount Acc of the accelerator pedal 88, irrespective ofa shifting action of the automatic transmission 16. The time chart ofFIG. 15 indicates changes of various parameters during an operation ofthe electronic control unit 90 to control the drive-power-engine torqueT_(PD) according to the drive-power-source-torque control routine ofFIG. 14. The drive-power-source-torque control routine will be describedby reference to the flow chart of FIG. 14, in the case where theautomatic transmission 16 is shifted down as a result of a gradualincrease of the operating amount Acc of the accelerator pedal 88.

The drive-power-source-torque control routine of FIG. 14 is initiatedwith step S1 corresponding to the vehicle-state detecting portion 108,to determine whether the vehicle is in a running state or not. Thisdetermination in step S1 is made on the basis of information including:the engine speed N_(E) detected by the engine speed sensor 99; theturbine speed N_(T) (=speed N_(IN) of the input shaft 22) detected bythe turbine speed sensor 91; the vehicle running speed V detected by theoutput-shaft-speed sensor 47; the opening angle θ_(TH) of theelectronically controlled throttle valve 62 detected by the throttleopening sensor 63; the operating amount of the vehicle acceleratingmember in the form of the accelerator pedal 88 detected by theaccelerator sensor 89; and the presently selected position P_(SH) of theshift lever 92. When the engine speed N_(E) is increased as a result ofdepression of the accelerator pedal 88 while the shift lever 92 isplaced in its neutral position N, that is, when a racing of the engine10 occurs with the shift lever 92 placed in the neutral position, orwhen the vehicle is driven in the reverse direction with the shift lever92 placed in its reverse drive position R, the engine torque T_(E) iscontinuously increased with an increase of the operating amount of theaccelerator pedal 88. If a negative decision (NO) is obtained in stepS1, one cycle of execution of the drive-power-source-torque controlroutine is terminated. If an affirmative decision (YES) is obtained instep S1, the control flow goes to step S2 also corresponding to thevehicle-state detecting portion 108, to read in the operating amount Accof the accelerator pedal 88 detected by the accelerator sensor 89, andoptionally the presently selected position of the automatic transmission16 which is determined by the shift control portion 100 according to thedata map representative of the shift-up and shift-down boundary lines ofFIG. 8.

Step S2 is followed by step S3 corresponding to the target-drive-forcesetting portion 106, to determine the target output torque T_(OUT)* ofthe automatic transmission 16 on the basis of the detected operatingamount Acc of the accelerator pedal 88 and the presently selectedposition of the automatic transmission 16, so that the actual outputtorque T_(OUT) of the automatic transmission 16 is smoothly changed witha change of the operating amount Acc. For instance, the target outputtorque T_(OUT)* is determined so that an amount of change of the outputtorque T_(OUT) after a shifting action of the automatic transmission 16is smaller than that before the shifting action, whereby the outputtorque T_(OUT) is smoothly changed with a change of the operating amountAcc of the accelerator pedal 88. Thick solid line in FIG. 12 indicatesan increase of the target output torque T_(OUT)* with an increase of theoperating amount Acc of the accelerator pedal 88 during which the twoshift-down actions of the automatic transmission 16 take place.

Step S3 is followed by step S4 corresponding to the shifting-completiondetermining portion 102, to determine whether a shifting action of theautomatic transmission 16 initiated (at a point of time t1 indicated inFIG. 15) under the control of the shift control portion 100 is completedor not. This determination in step S4 is made, for example, bydetermining whether the input shaft speed N_(IN) has becomesubstantially equal to the synchronizing input shaft speed (γ×N_(OUT)),which is a product of the output shaft speed N_(OUT) and the speed ratioγ of the position of the automatic transmission 16 established after theshifting action. The principle of the present invention is applicable toshifting actions of the automatic transmission 16 according to theshift-up and shift-down boundary lines of FIG. 8 under the control ofthe shift control portion 100. If a negative decision (NO) is obtainedin step S5, the control flow goes to step S5 corresponding to the secondcontrolling portion 112, in which the drive-power-source torque T_(PD)is controlled to maintain the present value of the output torque T_(OUT)of the automatic transmission 16. As described above, the continuouscontrol of the drive-power-source torque T_(PD) by the secondcontrolling portion 112 is effected by at least one of theelectronic-throttle-valve control of controlling the opening angleθ_(TH) of the electronically operated throttle valve 62, thesupercharging-pressure control of controlling the exhaust waste gatevalve 56 to control the supercharging pressure Pa of the supercharger 54of exhaust turbocharger type, and the engine-cylinder control ofcontrolling the valve drive control device 81 to control the number ofthe operable cylinders of the engine 10.

If an affirmative decision (YES) is obtained in step S4, the controlflow goes to step S6 corresponding to the first controlling portion 110,to initiate the transient or temporary control of the drive-power-sourcetorque T_(PD), at a point of time t2 indicated in FIG. 15. Namely, thetemporary or transient control of the drive-power-source torque T_(PD)in step S4 by the first controlling portion 110 is effected, to obtainthe target output torque T_(OUT)* determined upon completion of theshift-down action of the automatic transmission 16 initiated during agradual increase of the operating amount Acc of the accelerator pedal 88as indicated by the thick solid line in FIG. 12, for the predeterminedtransient control time t_(P) during which the operation of the secondcontrolling portion 112 is not effective to reduce thedrive-power-source torque T_(PD) which would abruptly increase as aresult of the shift-down action of the automatic transmission 16. Asdescribed above, the first controlling portion 110 having a higheroperating response than the second controlling portion 112 in thecapability to reduce the drive-power-source-torque T_(PD) employs atleast one of the ignition-timing control device arranged to effect theignition-timing control of retarding the ignition timing of the engine10 by controlling the ignition device 59, and the electric-motor-torquecontrol device arranged to effect the electric-motor-torque control ofcontrolling the torque T_(M) of the electric motor (motor/generator MG1and/or motor/generator MG2) by controlling the switching devices 72, 73to control amounts of electric current to be applied from the fuel cell70 and the secondary battery 71 to the first motor/generator MG1 and/orthe second motor/generator MG2.

Where the automatic transmission 16 is shifted down from the4^(th)-speed position to the 3^(rd)-speed position, for example, thisshift-down action causes an increase in the output torque T_(OUT) of theautomatic transmission 16 from the 4^(th)-speed torque value T_(OUT4) tothe 3^(rd)-speed torque value T_(OUT3). The ratio of the 3^(rd)-speedtorque value T_(OUT3) to the 4^(th)-speed torque value T_(OUT4) is equalto the ratio of the speed ratio γ3 of the 3^(rd)-speed position to thespeed ratio γ4 of the 4^(th)-speed position. Namely,T_(OUT3)=γ3/γ4·T_(OUT4). To reduce the difference between the3^(rd)-speed torque value T_(OUT3) and the 4^(th)-speed torque valueT_(OUT4) (the amount of change from the 4^(th)-speed torque valueT_(OUT4) to the 3^(rd)-speed torque value T_(OUT3)), thedrive-power-source torque T_(PD3) after the shift-down action is reducedby an amount corresponding to the ratio of the speed ratio γ4 of the4^(th)-speed position to the speed ratio γ3 of the 3^(rd)-speedposition. Namely, T_(PD3)=γ4/γ3·T_(PD4). Thus, the drive power source iscontrolled by the first controlling portion 110 to reduce thedrive-power-source torque T_(PD) to T_(PD3).

Step S6 is followed by step S7 corresponding to thetransient-control-time-lapse determining portion 114, to determinewhether the predetermined transient control time t_(P) has elapsed. StepS6 is repeatedly implemented until an affirmative decision (YES) isobtained in step S7. If the affirmative decision is obtained in step S7(at a point of time t3 indicated in FIG. 15), the control flow goes tostep S8 also corresponding to the second controlling portion 112, inwhich the amount of reduction of the torque T_(PD) by the secondcontrolling portion 112 is gradually increased while the amount ofreduction of the torque T_(PD) by the first controlling portion 110 isgradually reduced, so that the transient control by the firstcontrolling portion 110 is gradually switched to the continuous controlby the second controlling portion 112. The transient control time t_(P)may be replaced by a time period including a period (between points oftime t2 and t4 indicated in FIG. 15) in which the amount of reduction ofthe torque T_(PD) by the second controlling portion 112 is increased asthe amount of reduction of the torque T_(PD) is reduced. As a result ofthe transient and continuous controls of the drive-power-source torqueT_(PD) by the first and second controlling portions 110, 112, thedrive-power-source torque T_(PD) (e.g., engine torque T_(E)) after theshift-down action of the automatic transmission 16 is made smaller thanthat before the shift-down action, as indicated in FIG. 15, so that theoutput torque T_(OUT) (indicated by solid line in FIG. 15) of theautomatic transmission 16 after the shifting action is reduced withrespect to that (indicated by broken line in FIG. 15) controlled by theprior art vehicle control apparatus. As indicated in FIG. 15, the outputtorque T_(OUT) is reduced in the process of the shift-down action, dueto partially engaging states of the two frictional coupling deviceswhich are eventually engaged and released, respectively, such that theseengaging and releasing action take place substantially concurrently.

The drive-power-source-torque control portion 104 is thus arranged topermit a smooth or gradual change of the drive-power-source torqueT_(PD) with a gradual change of the operating amount Acc of theaccelerator pedal 88, for thereby permitting a smooth increase of theoutput torque T_(OUT) of the automatic transmission 16, as indicated bythick solid lines in FIGS. 12 and 13, irrespective of the shift-downaction of the automatic transmission 16, so that the vehicle drive forceF will not abruptly increase but smooth increase after the shift-downaction, whereby the vehicle can be driven with a high degree ofdrivability, without a considerable shifting shock of the automatictransmission 16 due to an abrupt increase of the vehicle drive force Fafter the shifting action.

In the vehicle control apparatus constructed according to the presentembodiment and operated as described above, the target-drive-forcesetting portion 106 (step S3) determines the target drive force F* inthe form of the target output torque T_(OUT)* of the automatictransmission 16 on the basis of the detected operating amount Acc of themanually operable vehicle accelerating member in the form of theaccelerator pedal 88 and the presently selected position of theautomatic transmission 16, such that the determined target drive forceF* permits a smooth change of the actual vehicle drive force F (actualoutput torque T_(OUT) of the automatic transmission 16) with an increaseof the operating amount Acc, irrespective of the shifting action of theautomatic transmission 16. Further, the first controlling portion 110(step S6) of the drive-power-source-torque control portion 104 effectsthe temporary or transient control of the drive-power-source torqueT_(PD), using at least one drive-power-source-torque control device(such as the ignition-timing control device and electric-motor-torquecontrol device) which has a comparatively high operating response, andthe second controlling portion 112 (steps S5 and S8) effects thecontinuous control of the drive-power-source torque T_(PD) following thetransient control by the first controlling portion 110, by using atleast one drive-power-source-torque control device (such aselectronic-throttle-valve control device, supercharging-pressure controldevice and valve-drive control device) which is capable of continuouslycontrolling the torque T_(PD) for a relatively long time. In thisarrangement, the output torque T_(OUT) of the automatic transmission 16is smoothly changed with a change of the operating amount Acc of theaccelerator pedal 88, without an abrupt change of the torque T_(OUT)upon a shifting action of the automatic transmission 16, so that anabrupt change of the vehicle drive force F after the shifting action isprevented to improve the drivability of the vehicle. It is alsoappreciated that the above-indicated drive-power-source-torque controldevices used as the first and second controlling portions 110, 112 ofthe drive-power-source-torque control portion 104 are available on thevehicle and need not be provided as control devices exclusively designedfor the purpose of controlling the drive-power-source torque T_(PD) soas to permit a smooth change of the vehicle drive force F upon ashifting action of the automatic transmission 16.

While the drive power source in the present embodiment consists of theengine 10 and the two electric motors (MG1 and MG2), thedrive-power-source torque T_(PD) can be controlled by the firstcontrolling portion 110 (step S6) by controlling at least one of theengine torque T_(E) and the electric motor torque T_(M) (at least one ofthe torque of the MG1 and the torque MG2), namely, by using at least oneof the ignition-timing control device arranged to control the ignitiontiming of the engine 10 to control the engine torque T_(E), and theelectric-motor-torque control device arranged to control the electricmotor torque T_(M). Accordingly, the drive-power-source torque T_(PD)can be controlled with a high response to the output signal of theshifting-completion determining portion 102.

Further, the second controlling portion 112 (steps S5 and S8) may beprovided by at least one of the electric-throttle-valve control devicearranged to control the opening angle θ_(TH) of the electronicallycontrolled throttle valve 62, the supercharging-pressure control devicearranged to control the supercharging pressure of the supercharger 54,and the valve-device control device arranged to control the number ofthe operable cylinders of the engine 10. These devices are capable ofcontinuously controlling the drive-power-source torque T_(PD) for arelatively long time.

While the preferred embodiment of this invention has been described indetail by reference to the accompanying drawings, it is to be understoodthat the invention may be otherwise embodied.

In the illustrated embodiment, the drive-power-source torque T_(PD) iscontrolled so as to permit a smooth increase of the output torqueT_(OUT) of the automatic transmission 16 (vehicle drive force F), whenthe automatic transmission 16 is shifted down from the 4^(th)-speedposition to the 3^(rd)-speed position as a result of a gradual increaseof the operating amount Acc of the accelerator pedal 88. However, theprinciple of this invention is equally applicable to shift-down actionsof the automatic transmission 16 from the 5^(th)-speed position to the4^(th)-speed position, from the 3^(rd)-speed position to the2^(nd)-speed position, and from the 2_(nd)-speed position to the1^(st)-speed position. The principle of this invention is furtherapplicable to shift-up actions of the automatic transmission 16, whichtake place as a result of a gradual decrease of the operating amount Accof the accelerator pedal 88. The target output torque values T_(OUT)* ofthe automatic transmission 16 indicated by the thick solid lines in FIG.12 can be used for controlling the drive-power-source torque T_(PD) upona shift-up action of the transmission 16. In this case, the outputtorque T_(OUT) after the shift-up action is reduced with respect to thatbefore the shift-up action, so that the drive-power-source torque T_(PD)must be increased by the drive-power-source-torque control portion 104,so as to permit a smooth decrease of the output torque T_(OUT).

In the illustrated embodiment, the temporary or transient control of thedrive-power-source torque TPD by the first controlling portion 110 (stepS6) is initiated when the shifting-completion determining portion 102(steps S4) has determined that a shifting action of the automatictransmission 16 is completed. However, the transient control by thefirst controlling portion 110 may be initiated before completion of theshifting action, for instance, a predetermined time before completion ofthe shifting action, for example, when a difference between theinput-shaft speed N_(IN) and the synchronizing input-shaft speed(γ×N_(OUT)) has been reduced to about 50 r.p.m.

While the fluid-operated power transmitting device in the form of thetorque converter 14 is provided with the lock-up clutch 26, thefluid-operated power transmitting device need not be provided with thelock-up clutch 26. Further, the fluid-operated power transmitting deviceneed not have a torque boosting function.

In the illustrated embodiment, the drive power source consists of theinternal combustion engine 10, and the first motor/generator MG1 and thesecond motor/generator MG2 which are operatively connected to the engine10. However, the drive power source consists of at least one of theengine 10, MG1 and MG2. The internal combustion engine 10 may be agasoline engine or a diesel engine. Further, the engine 10 need not beprovided with the supercharger of exhaust turbocharger type disposed soas to bridge the intake and exhaust pipes 50, 52. The motor/generatorMG1 and motor/generator MG2 may be directly connected to the engine 10,or indirectly connected to the engine through a belt or any otherconnecting means. Where the drive power source consists of only themotor/generator MG1 and/or the motor/generator MG2, only theelectric-motor-torque control device is available as the firstcontrolling portion 110 for controlling the drive-power-source torqueT_(PD).

The engine 10 in the illustrated embodiment is provided with thevariable valve mechanism 78 including electromagnetically operatedvalves in the form of the intake and exhaust valves 74, 75 that areopened and closed by the respective electromagnetic actuators 76, 77.However, only one of the intake and exhaust valves 74, 75 may beelectromagnetically operated. Further, the engine 10 need not beprovided with the variable valve mechanism 78. The intake and exhaustvalves 74, 75 may be operated by electric actuators such as electricmotors, or by a valve drive mechanism which is arranged to open andclose the intake and exhaust valves in synchronization with the rotarymotion of the crankshaft of the engine 10 and which is equipped with avalve timing mechanism arranged to adjust the opening and closingtimings of the intake and exhaust valves. The valve drive mechanism maybe of an OHV type, an OHC type or a DOHC type. In the valve drivemechanism of the DOHC type, the rotary motion of the crankshaft of theengine is transmitted to the intake valve or exhaust valve through apulley on the crankshaft, a timing belt, a pulley on a cam shaft, thecam shaft, and a rocker arm or valve lifter connected to the intake orexhaust valve. In this type of engine, the valve timing device may beprovided on the rocker arm or cam shaft pulley, or on at least one ofthe two cam shafts for the respective intake and exhaust valves, suchthat the synchronization timing of the two cam shafts is variable.Alternatively, the characteristic (profile) of the cam shafts is changedor switched to change the lift, opening angle or opening and closingtimings of the valves, so that the engine speed and torque can beadjusted as needed.

Although the automatic transmission 16 incorporates the three planetarygear sets 40, 42, 44 and has the five forward drive positions, thevehicle drive system may use an automatic transmission of any othertypes which is shiftable by engaging and releasing hydraulicallyoperated frictional coupling devices such as clutches and brakes. Forexample, the automatic transmission 16 may be modified to incorporatetwo, four or more planetary gear sets or to have four forward drivepositions, or six or more forward drive positions. Further, the vehicledrive system may use an automatic transmission which is obtained byproviding a well known manual transmission of permanent meshing paralleltwo axes type with selecting and shifting cylinders for automaticshifting of the transmission.

While the clutches C and brakes B used for the automatic transmission 16in the illustrated embodiment are hydraulically operated frictionalcoupling devices, the automatic transmission may use electromagneticallyoperated frictional coupling devices such as electromagnetic clutchesand magnetic powder type clutches.

It is to be understood that the present invention may be embodied withvarious other changes, modifications and improvements, which may occurto those skilled in the art, without departing from the spirit and scopeof the invention defined in the following claims.

1. An apparatus for controlling an automotive vehicle having a drivepower source, a transmission having a plurality of operating positionsthat are selectively established, and a manually operable vehicleaccelerating member, comprising: a target-drive-force setting portionoperable to determine a target vehicle drive force on the basis of anoperating amount of the manually operable vehicle accelerating memberand a presently selected one of said plurality of operating positions ofthe transmission, such that the determined target vehicle drive forcepermits a smooth change of an actual vehicle drive force with a changeof the operating amount of said vehicle accelerating member,irrespective of a shifting action of the transmission; a firstcontrolling portion having a relatively high operating response andoperable to effect a transient control of a torque of the drive powersource after completion of said shifting action of the transmission, sothat the actual vehicle drive force coincides with said target vehicledrive force after the completion of the shifting action of thetransmission; and a second controlling portion having a lower operatingresponse than said first controlling portion but is capable ofcontinuously controlling the torque of the drive power source, saidsecond controlling portion being operable to effect a continuous controlof the torque of the drive power source following said transient controlby said first controlling portion, so that the actual vehicle driveforce coincides with said target vehicle drive force after the shiftingaction of the transmission.
 2. The apparatus according to claim 1,wherein said drive power source device includes at least one of anengine and an electric motor, and said first controlling portionincludes at least one of an ignition-timing control device operable toeffect an ignition-timing control of adjusting an ignition timing of theengine, and an electric-motor-torque control device operable to effectan electric motor torque control of controlling a torque of the electricmotor.
 3. The apparatus according to claim 1, wherein said secondcontrolling portion includes at least one of anelectronic-throttle-valve control device operable to effect anelectronic throttle valve control of controlling an opening-angle of anelectronically controlled throttle valve of the engine, asupercharging-pressure control device operable to effect a superchargingpressure control of controlling a supercharging pressure of asupercharger of the engine, and a valve drive control device operable toeffect an engine cylinder control of controlling the number of operablecylinders of the engine.
 4. The apparatus according to claim 1, furthercomprising a memory storing a data map representative of a predeterminedrelationship among the target vehicle drive force, the operating amountof the manually operable vehicle accelerating member and said pluralityof operating positions of the transmission, and wherein saidtarget-drive-force setting portion determines said target vehicle driveforce on the basis of the operating amount of the manually operablevehicle accelerating member and the presently selected position of thetransmission, and according to said predetermined relationship.
 5. Theapparatus according to claim 1, wherein the target vehicle drive forcesetting portion determines a target output torque of the transmission soas to reduce an amount of change of the output torque of thetransmission before and after the shifting action of the transmission.6. The apparatus according to claim 1, wherein said shifting action ofthe transmission is a shift-down action, and said first controllingportion effects said transient control to temporarily reduce the torqueof said drive power source for a period of time after a moment ofcompletion of said shift-down action of said transmission, during whichan operation of said second controlling portion is not effective toreduce the torque of the drive power source, said transient control ofthe torque of the drive power source by said first controlling portionis switched to said continuous control by said second controllingportion, after said period of time, such that an amount of reduction ofthe torque of the drive power source by said first controlling portionis continuously reduced as the torque of the drive power source iscontinuously reduced by the second controlling portion.
 7. The apparatusaccording to claim 1, further comprising a shifting-completiondetermining portion operable to determine whether the shifting action ofthe transmission is completed, and a transient-control-time-lapsedetermining portion operable to determine whether a predeterminedtransient control time has passed after a moment of determination bysaid shifting-completion determining portion that the shifting action iscompleted, said transient control of the torque of the drive powersource by said first controlling portion is effected for thepredetermined transient time, and is switched to said continuous controlby said second controlling portion at a moment of determination by saidtransient-control-time-lapse determining portion that the predeterminedtransient control time has passed.
 8. The apparatus according to claim7, wherein the shifting action of the transmission is a shift-downaction, and wherein the transient control of the torque of the drivepower source by the first controlling portion is gradually switched tothe continuous control by the second controlling portion such that anamount of reduction of the torque of the drive power source by the firstcontrolling portion in a direction that permits said smooth change ofthe actual vehicle drive force is gradually reduced while an amount ofreduction of the torque of the drive power source by the secondcontrolling portion in said direction is gradually increased.
 9. Theapparatus according to claim 1, further comprising a shifting-completiondetermining portion operable to determine whether the shifting action ofthe transmission is completed; and a transient-control-time-lapsedetermining portion operable to determine whether a predeterminedtransient control time has passed after a determination that theshifting action is completed.
 10. The apparatus according to claim 9,wherein after expiration of the transient control time, an amount ofreduction of the drive power source by the first controlling portion isgradually reduced as an amount of reduction of the drive power source bythe second controlling portion is gradually increased.